When the laser radiation is emitted at nanoseconds and picoseconds pulses and the power density is in the range of the GW and the laser light is absorbed by clusters or particles of ink or melanosomes, it generates an extremely rapid rise of temperature up to more than 900° C(1). This rapid heating induces an extremely fast expansion in the target, which generates a mechanical wave (acoustic)that crosses over the target itself. The generated wave exerts a pressure that exceeds the fracture threshold of the target, causing its fragmentation(2). Thereafter, the fragments can undergo phagocytosis by macrophages and be removed through the lymphatic system. This is the process called photoacoustic effect which is literally able to “pulverize” particles. To make this happen at the best conditions, the laser pulse duration must shorter than the time of crossing over of the mechanical wave within the target, which for ink clusters is in nanoseconds and for the smallest ink particles and single melanosomes is in the picosecond range, all this leaving the surrounding tissues unaffected. The picosecond YAG laser can break down the smallest ink particles which compose the black tattoos. This color, due also to the very small dimensions of its particles, sometimes become resistant to Q-Switched treatments showing small improvements at every session. The picosecond pulse can fragments even the smallest black ink particle in a really thin “dust”, which is easier to be eliminated by the body immune system. By emitting at both 532 nm and 1064 nm wavelengths at picosecond regime, Discovery PICO can treat different tattoo colors, superficial and deep pigmented lesions by using also the Q-Switched emission modes. As an exclusive feature of this laser, the Photo-Thermal mode permits to treat also the aged skin (skin rejuvenation) effectively.

 

​(1) Basics in Dermatological Laser Applications, Inja Bogdan Allemann, D. J. Goldberg – 2011 (2) (Comparison of Response of Tattoos to Picosecond and Nanosecond Q-Switched Neodymium:YAG Laser - E. Victor Ross, USN; George Naseef, MD; Charles Lin, PhD;Michael Kelly, MS; Norm Michaud, MS; Thomas J. Flotte, MD; Jill Raythen;R. Rox Anderson, MD, Arch Dermatol. 1998;134(2)

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